1. Field of the Invention
The present invention concerns a polymeric separator for an organic electrolyte electrochemical system, and a process for its production.
It also concerns an electric cell comprising the separator of the invention and a process for the production of an electric cell comprising that separator.
2. Description of the Prior Art
"Solid" organic electrolyte electrochemical systems, in particular cells and supercapacitors, include electrodes around a layer of porous electrically insulative material impregnated with electrolyte, termed a separator.
The separator must have good intrinsic mechanical behavior and a good affinity for the organic electrolyte. Polymeric materials, in particular polyvinylidene fluoride (PVDF) satisfy those two criteria and are conventionally used for the separator.
Polyvinylidene fluoride (PVDF) in particular is widely used. However, as it dries, a PVDF based separator tends to undergo large dimensional variants which can result in the electrode and separator, or even the electrode and the metallic current collector, separating.
The present invention proposes a polymeric separator for an organic electrolyte electrochemical system in which dimensional variants are minimized, by replacing some or all of the PVDF by an elastomeric polymer or by an alloy of an elastomeric polymer with a polymer which swells in the electrolyte.